For the chicken: Combine the flour and black pepper in large Ziploc bag. Add the chicken and shake to coat with flour mixture. Heat oil in skillet over medium-high heat. Brown chicken about 2 minutes on each side. Place chicken in slow cooker.
FOR THE SAUCE: Note: If you like it really saucy over rice, consider doubling the sauce. Combine soy sauce, vinegar, ketchup, sugar, garlic, ginger, and pepper flakes in small bowl; pour over chicken. Cook on LOW for 3-4 hours. Add cashews and stir. Serve over white rice.
INSTANT POT INSTRUCTIONS: Combine sauce in step two and add to the instant pot. Add the chicken and toss to coat. Lock the lid and turn valve to "sealing". Set the manual/pressure cook button to 6 minutes on high pressure. Turn the valve to venting. After pressure has released, remove the lid. In a small bowl, make a slurry with 1 tablespoon cornstarch and 1 tablespoon water. Stir into the instant pot and turn on the Sautee function for 2-3 minutes or until sauce thickens. Add cashews and stir. Serve over rice. Garnish with green onions or chopped cilantro if desired.
